Apparatus for the cementing of shoes



June 8, 1943. E. L. CRANDELL APPARATUS FOR THE CEMENTING OF SHOES Filed April 26, 1941 3 Sheets-Sheet 1 lune 8, 1943. E. L. CRANDELL 2,321,130

APPARATUS FOR THE CEMENTING OF SHOES Ffiled April 26, 1941 3 Sheets-Sheet 2 jiw zzmzimw Z 6. Elwin/Z. fimmaiez June 8, 1943. E. L. CRANDELL APPARATUS FOR THE CEMENTING OF SHOES Patented June 8, 1943 UNITED STATES PATENT OFFICE APPARATUS FOR THE CEMENTING OF SHOES Application April 26, 1941, Serial N0. 390,555

7 Claims.

This invention relates to apparatus for cementing shoe parts. and relates more particularly to apparatu utilizing high frequency electrostatic energy for heating adhesive between outsoles and the shoes to which they are to be cemented.

This invention provides a plurality of individual features which cooperate to enable high frequency electrostatic fields to be used in conveyor systems for the more rapid cementing of shoe parts and the improvement in quality of the cemented shoes.

One feature of this invention resides in the provision of a. plurality of heating stations for each shoe. Preferably a plurality of high frequency oscillators are provided, the heating electrodes for each hoe being connected successively to the individual oscillators. Each shoe is thus heated a plurality of times with a reduction in the overall time required for heating and with improvement in quality since the voltage between the electrodes in the individual stations is reduced, resulting in the eliminaton of burns.

Another feature of the invention resides in the provision of signals such as neon lamps with each of the plurality of oscillators for indicating whether or not they are in service.

Another feature of the invention resides in directly connecting the heating electrodes for each shoe, successively to the anode circuits of the individual oscillators, thereby eliminating the necessity for retuning the individual oscillators as the capacity of the shoe circuit changes during the heating cycle.

Another feature of the invention resides in grounding the shoe supporting jack frames of the individual presses at their opposite ends through brush contacts thereby eliminating the parasitic electric voltages developed across the jack frames as they move through the high frequency fields.

An object of the invention is to reduce the time required for cementing shoe parts through high frequency, electrostatic energy.

Another object of the invention is to improve the quality of shoes having parts cemented by high frequency electrostatic energy.

The invention will now be described with reference to the drawings, of which:

Fig. 1 is'a plan view looking downwardly upon a conveyor system embodying features of this invention;

Fig. 2 is a front elevation of the conveyor of Fig. 1;

Fig. 3 is an enlarged view of one oscillator station with its cover removed, and of one shoe press having electrodes directly connected to the oscillator;

Fig. 4 is a plan view of interlaced electrodes which may be used for connection to the two sides of the oscillator circuits;

Fig. 5 is a sectional view taken along the lines 5-5 of Fig. 1;

Fig. 6 is a view taken along the line 6-6 in the direction of the arrows, of Fig. 3, and

Fig. 7 is a circuit diagram illustrating the electric power supply, the electric controls, and the circuit details of the individual oscillatorsused with the conveyor systems of Figs. land 2.

The U. S. Patent No. 2,087,480 to E. C. Pitman discloses generally the utilization ofhigh frequency, electrostatic energy for the heating of thermoplastic adhesives for the cementing of hoe parts, such as outsoles to the bodies of shoes, and the Smith Patent No. 2,109,323 discloses a .con veyor system utilizing the teachings of the Pit- A man patent for the quantity production of shoes.

The present invention utilizes a conveyor system such as shown in the Smith patent and adds to it the previously indicated features whereby the rate of production of shoes is increased, and their quality is improved.

Referring now to the drawings, the conveyor illustrated by Figs. 1 and 2 is similar to that disclosed in the Smith Patent No. 2,169,981 in that a motor I0 rotates through the gear box II and the conveyor drive pulleys II, the belt l3 on which the plurality of shoe presses H are mounted. The details of the presses and the pads carried thereby are fully disclosed and described in the said Smith patents and so are not described herein. The differences of the apparatus of Figs. 1 and 2 as well as that of the other figures of the drawings from the prior disclosures reside in the provision of a plurality of heating stations, each utilizing a separate high frequency oscillator; the connections of the heating electrodes of each shoe press, in succession to each of the oscillators by brush contacts; the provision of neon lamps for indicating the condition of the individual ocillators, and the grounding of the jack frames of the individual presses, at each end thereof, through brush contacts. The applications of these novel features and their functions will now be described.

Six heating stations utilizing the six oscillator stations l5 are provided in the present embodiment. Two or more stations could be used without departure from the essence of this invention.

With reference to Fig. 7, each oscillator station comprises a single ended power triode 16 which has connected to its control grid and to its anode, the tank coil l1. One end of the coil I1 is connected through a blocking condenser to the anode of the tube l8, and the other end of the coil I1 is connected to the grid of the tube l6 through a grid leak and condenser, as illustrated. The anode of the tube is connected to a standard rectifier unit indicated generally by l8, through the radio frequency choke l9 and the positive, D. C. leads 20. The stations are individually enclosed by metal grounded shields for preventing electrical interaction.

The negative lead 22 from the rectifier unit I8 is grounded at 23 to the metal frame of the conveyor, and is connected to the center tap of the secondary of the filament transformer 24, and to the tap 25 on the tank coil II. The tap 25 is connected to ground at 26 adjacent the coil l1, and to the brush 28 which is grounded at21.

The brush 28 contacts the inner end of the jack frame 29 and. connects through the flexible metal strip 30, one of the electrodes 3| to the ground side of the oscillator.

The brush 32 is connected to the tap 33 o the tank coil 11 and connects through the commutator contact 34, and'the flexible lead 35, the electrode 36 to the live 'side of the oscillator circuit.

The taps 25 and 33 are adjustable on the coil I! so that the individual oscillator circuits may be adjusted for producing the required frequency and current density.

Due to the high frequencies involved and to the distributed capacities of the jack frames 29 upon which the inflatable pads and the heating electrodes are mounted, parasitic voltages are induced in the jack frames. To eliminate these parasitic voltages, the brushes are connected to the frame of the conveyor at 48, and contact the outer edges of the jack frames 29 thus grounding their outer edges. The inner edges are grounded at 21 through the brushes 28 so that there can be no voltage drop across the jacks.

The neon lamps 31 are connected to ground at one side and to the tap 38 on the oscillator coil I! at the other side. They are adjusted so that they glow when the oscillators with which they are associated, are operating properly and thus serve to signal the operator of the conveyor, so that in case one or more of the oscillators are not functioning properly, he can stop the conveyor and have the defective oscillator serviced. Otherwise the quality of the shoes would be adversely affected through lack of the appllcationof proper degree of heat during the heating cycle.

The electrodes 31 and 36 are preferably in the form of flat plates and are arranged within a flexible leather pad 39 which in turn, is placed upon the inflatable pad 40. These electrodes cooperate with an electrode which is capacity coupled thereto and which may be a metal plate upon the bottom of the last 4| as disclosed in said Smith Patent No. 2,109,323, or which may be an electrode contained within the shoe as disclosed in my copending application Serial No. 387,823.

In the cementing of shoes, it is customary to roughen the bottom of the lasted shoe and the top of the outsole and to coat them with an adhesive such, for example, as thermoplastics in solution, as disclosed in said Pitman patent, the adhesive then being permitted to dry, following which, the shoe assembly is placed in the press as illustrated by Fig. 5.

Upon the application of the high frequency electrostatic energy from the oscilaltor tank coil 11 to the electrodes 3i and 36, an intense electric field is set up between their upper surfaces and the capacity coupled electrode placedupon the other side of the adhesive as more fully disclosed in my copending application, Serial No. 391,293. The electric field causes as explained in said Pitman patent, heat to be generated in theadhesive coatings causing them to soften and to adhere to the shoe parts and to cement them together.

In prior systems, it was customary to heat the shoe in but a single stage. This required a comv bination of an electrostatic field intensity and a period of time which proved impractical for quantity production. It was possible to shorten the time interval by increasing the intensity of the electric field and accordingly the degree of heat in the adhesive. This however, resulted in burns and other disadvantages. By reducing the radio frequency voltage, it was possible to improve the quality of the shoes but the time interval was too long.

According to this invention, each shoe is heated a plurality of times and at the same time a plurality of shoes are proceeding through the heating cycle. Each shoe circuit therefore receives the correct amount of voltage in successive steps and the speed of the conveyor is speeded up to that required for quantity production.

By providing individua1 oscillators for each heating stage and by directly connecting the shoe heater circuits to the oscillator anode circuits, the oscillators are loaded uniformly and the necessity for returning the oscillator circuits as the capacity of the shoe circuit changes during the heating, is eliminated. The change in the capacity of the shoe circuit causes a change in the frequency of the direct coupled oscillator but the amperage is substantially unchanged. Single ended oscillators as illustrated by the drawings, are preferred, for in push-pull tube circuits, the circuits would be unbalanced with one tube overloaded resulting in a low circuit efllciency.

By direct connection of the shoe circuits or of the shoe heating electrodes, to the oscillators is meant non-inductive connections to the anodes of the oscillators. The shoe circuits have capacities including. those of the presses, which capacities'are coupled directly and not inductively to the oscillator anodes.

The type of conveyor used, the inflatable pads, the presses and mechanical controls with which the features of this invention are used, are disclosed not only in the said Smith patents .but also in the Weiss Patent No. 1,945,762. Accordingly in the following explanation of the operation of the apparatus disclosed herein, only such description of novel features and of such cooperating apparatus as is believed to be necessary for an understanding of their functioning, will be made. The circuit details of the control apparatus are disclosed in the Smith application, Serial No. 284,080, and so will not be described herein, since forming no part of this invention.

The operator first places a shoe in a press at the loading station as illustrated by Fig. l, and then depresses pedal 86 to inflate the pad and then operates the foot pedal 50 (Figs. 1 and 2) which closes the foot station switch 5| which closes the energizing circuit of the magnetic switch 52 which closes contacts to energize the conveyor motor l0 causing the conveyor to start moving. The conveyor moves until the limit switch 53 is opened by movement of the presses on the conveyor into the proper heating positions as disclosed in detail in the said Smith application, Serial No. 284,080. This causes the magnetic switch 52 to disconnect the motor I. and at the same time to cause the timer relay N to actuate the timer 55 which controls throus the contactor 56, the supply of energy from the rectifier unit I! to the oscillator units l5 and which is adjustable to maintain the oscillators energized a predetermined time which experience has shown to be sufficient for the proper heating of the shoes.

The timer relay 54 controls the safety relay II which prevents the magnetic switch 52 from energizing the motor it before the timer 5! has operated through the heating cycle.

The time delay relay 51 is connected to delay the supply through the transformer SI of high voltage to the rectifier tubes until their filaments have been heated through the supply of filament voltage through the transformer 59.

The overload relay ll is arranged to discon-. nect the high voltage supply from the rectifier upon an abnormal increase in current. It incorporates a reset control for enabling the circuit to be again closed.

The push button switch I is connected to the magnetic switch 52 so that the conveyor can be started and stopped by hand .as well as by foot pressure.

The solenoid 62 is energized by the magnetic switch 52 when the motor I0 is energized and acts to deflate the pads after the heating cycle and prior to loading shoes thereon.

The counter relay '4 is connected to cause the counter 65 to count one when the motor II has moved the presses through one heating and one inflation cycle.

The inflation switch 86 is actuated to operate through the magnetic switch 52 to open the circuit of the conveyor motor it when the inflating chuck is advanced towards a press.

Thus each press I is loaded with a shoe assembly, the pad 40 is then inflated to apply pressure to the shoe elements, and the presses are then moved in succession so that the brushes 1!. l2 and 45 of each oscillator unit I! contact connections to the electrodes of eachjpad 39,

and of the jack frames 29, the presses being held in alignment with the oscillator units for predetermined periods 0! time for the applications of the high frequency heating fields.

The radio frequency energy being applied in a I plurality of steps, has its voltage reduced so that no burns can occur. At the end of the heating cycle-in this embodiment at the end of the heat applied in the sixth heating stationthe required amount of heat and no more has been applied and this has been accomplished at relatively high speed since not only is each shoe assembly heated six times but six shoe assemblies are heated simultaneously.

After leaving the last heating station, the pressure of the pads is maintained during movement of the conveyor, up to the deflating station during which movement, the shoe assemblies have cooled and the cement has set. The

presses are then unloaded and then reloaded with other shoe elements.

By way of example, an oscillator frequency of 20 megacycles has been found satisfactory for the practice of this invention.

The novel features of this invention while they cooperate to speed up production and to improve the quality of shoes, could be used separately for improved results.

While one embodiment of the invention has been described for the purpose of illustration, it should be understood that the invention is not limited to the exact apparatus. and combinations and arrangements of apparatus illustrated, as modifications thereof may be suggested by those skilled in the art without departure from the essence of the invention.

What is claimed is:

1. In apparatus for cementing shoe parts to- Y gether and including a plurality of shoe presses. and a conveyor for moving said presses successively through a cement heating zone, each of said presses including a pair of electrodes for electrically heating the cement between shoe parts supported in said presses; the combination of a plurality of oscillators alongside said conveyor in said zone for supplying high frequency, electrostatic fields between said electrodes; means for grounding one of the electrodes of each'of said presses and one side of the output circuit of each of said oscillators, and means for connecting electrically the other electrode of each of said presses in succession to the other side of the output circuit of each of said oscillators as said presses move through said zone.

2. In apparatus for cementing shoe parts together and including a plurality of shoe presses, and a conveyor for moving said presses successively through a cement heating zone, each of said presses including a pair of electrodes for electrically heating the cement between shoe parts supported in said presses; the combination of a plurality of oscillators in alignment alongside said conveyor in said zone for supplying high frequency, electrostatic fields between said electrodes; means for grounding one side or the output circuit of each or said oscillators, and means including means in alignment with each of said oscillators for connecting electrically the electrodes of each of said presses in succession to the other side of the output circuit of each of said oscillators and for grounding the other .electrode of eac'lf-of said presses as said presses move through" said zone.

3. In apparatus for cementing shoe parts together and including a plurality of shoe presses, and a conveyor for moving said presses through a cement heating zone, said presses including electrodes ior electrically heating the cement between shoe parts supported above metal lack frames in said presses; the combination of high frequency oscillator means; means for connecting one of the said electrodes in each of said presses to the Jack frame of its respective press, means for electrically grounding said jack frames: means for grounding one side of the output circuit of said oscillator means, and means for connecting electrically another of the electrodes in each of said presses successively to the other side of said circuit.

4. In apparatus for cementing shoe parts together and including a plurality of shoe presses, and a conveyor for moving said presses through a cement heating zone, said presses including electrodes for electrically heating the cement between shoe parts supported above metal Jack i'rames in said presses; the combination of high frequency oscillator means, means for connecting one of the said electrodes in each of said presses to the Jack frame of its respective press; means for connecting electrically another of the electrodesin each of said presses successively to one side of the circuit of said oscillator means, and means for grounding the other side of said circuit and the frame associated with the said electrode connected to said one side of said circuitconcurrently with the connection of said last mentioned electrode with said one side of said circuit.

5. In apparatus for cementing shoe parts together and including a plurality of shoe presses. and a conveyor for moving said presses through a cement heating zone, said presses including electrodes for electrically heating the cement between shoe parts supported above metal jack frames in said presses; the combination of high frequency oscillator means, means for connecting one of the said electrodes in each of said presses to the jack frame of its respective press; means for connecting electrically another of the electrodes in each of said presses successively to one side of the circuit of said oscillator means, and means for grounding the other side of said circuit and the opposite ends of the frame associated with the said electrode connected to said one side of said circuit concurrently with the connection of said last mentioned electrode with said one side of said circuit. r

6. In apparatus for cementing shoe parts to gether and including a plurality of shoe presses, and a conveyor for moving said presses through a cement heating zone, said presses including electrodes for electrically heating the cement between shoe parts supported above metal jack iii frames in said presses; a plurality of high frequency oscillators; means for electrically connecting one electrode of each of said presses successively to one side of the output circuit of= each of said oscillators; means for electrically connecting another of the electrodes in each of said presses to its respective frame; means for grounding the other side of said circuit, and means for grounding the one of said frames associated with said one electrode connected to said one side of said circuit concurrently with the connection of said one electrode to said one side of said circuit.

7. In apparatus for cementing shoe parts together and including a plurality of shoe presses, and a conveyor for moving said presses through a cement heating zone, said presses including electrodes for electrically heating the cement between shoe parts supported above metal jack frames in said presses; a plurality of high frequency oscillators; means for electrically connecting one electrode of each of said presses successively to one side of the output circuit of each of said oscillato'rs; means for electrically connecting another of the electrodes in each of said presses to its respective frame; means for grounding the other side of said circuit, and means for grounding the opposite ends of the one of said frames associated with said one electrode connected to said one side of said circuit concurrently with the connection of said one electrode to said one side 01' said circuit.

ERVIN L. CRANDELL. 

